1. Field of the Invention
This invention relates to a magnetic recording medium, a method of manufacture therefor, and for an apparatus for magnetic recording and reproducing using this magnetic recording medium.
2. Description of the Related Art
So-called perpendicular magnetic recording media, in which the axis of easy magnetization within the magnetic film is arranged generally perpendicularly, have received a great deal of attention because the effect of the demagnetizing field at the bit boundaries is small even when high recording density has been realized, it is possible to achieve noise reduction due to the formation of magnetic recording domains which have distinct boundaries, and moreover, for having strong thermal fluctuation effects because it is possible to realize high recording density even if the comparative bit volume is large.
For example, in Japanese Patent Application, First Publication No. Hei 7-44852, a magnetic recording medium having a perpendicular magnetic film comprising a CoCrPtTa alloy and soft magnetic backlayer is disclosed.
In Japanese Patent Application, First Publication No. Hei 5-334644, a magnetic recording medium having a perpendicular magnetic film comprising an alloy in which V has been added to a CoCrTa alloy is disclosed.
In Japanese Patent Application, First Publication No. Hei 5-343225, a magnetic recording medium having a perpendicular magnetic film comprising an alloy in which B has been added to a CoCrTa alloy is disclosed.
In Japanese Patent Application, First Publication No. Hei 11-296833, a magnetic recording medium having a perpendicular magnetic film having a two-layered structure is disclosed.
For perpendicular magnetic recording media, in order to obtain magnetic characteristics such as coercive force and squareness ratio, it is important to increase the perpendicular orientation in the perpendicular magnetic film.
However, with conventional magnetic recording media, when the orientation of the perpendicular magnetic film becomes better, since the direction of the growth of the crystals becomes uniform, the distance between the magnetic grains becomes smaller, and noise due to the effect of the exchange coupling increases.